A superconducting cable includes a cable core and a thermal insulation tube which has a vacuum double tube structure to contain the cable core wherein the cable core is formed by a superconductive conductor layer, an insulating layer, a shield layer and the like are layered around a former. A multilayer thermal insulator (Super Insulation) is intervened between the double tube structure and very low temperature liquid cooling medium (for example, liquid nitrogen) for cooling the cable core circulates inside the thermal insulation tube.
When using the superconducting cable as a power supply line, the superconducting cable needs to be laid out to a power consuming site far from the power source. However, single long cable has limitations in view of manufacturing or shipping of the superconducting cables. Therefore, when laying out the cable for a long distance, number of superconducting cables need to be connected to each other.
At the intermediate connection unit where the superconducting cables are connected, a reinforcement insulating layer is formed around the superconductive conductor layers. By providing a shield connection body which covers around the reinforcement insulating layer and which connects with the shield layer, the magnetic field which occurs when a large amount of current flows in the superconductive conductor layer does not leak outside from the intermediate connection unit (for example, see patent document 1).